This paper specifically explains the principal causes of beach 

 erosion and accretion and determines the principles which control these 

 actions. Two examples are given, one in France and the other in Brazil, 

 where works have been constructed that fully illustrate the principles 

 enumerated, confirming the conclusion. 



148. SAKURAMOTO, H., HORIKAWA, K. , and SASAKI, T., "Prediction of Shore- 

 line Changes Due to Coastal Structures," Prooeedings of the S2d 

 Annual Convention^ Japan Society of Civil Engineers. 



149. SASAKI, T., "Simulation on Shoreline and Nearshore Current," Pvo- 

 oeedings of the Conference on Civil Engineering in the Oceans III» 

 American Society of Civil Engineers, 1975, pp. 179-196. 



Keywords: Accretion, Currents, Detached breakwater, Downdrift beaches, 



Littoral transport. Numerical model, Tombolo, Wave diffraction 



Two simulation models on nearshore environments were developed. 

 The first model is for predicting shoreline deformation behind a detached 

 breakwater placed parallel to the shoreline, and the second is for simu- 

 lating currents in the nearshore zone under the influence of an arbitrary 

 bottom topography. The former model was tested by laboratory experiments 

 (Horikawa and Koizumi, 1974), and the latter was verified by field obser- 

 vations, 



150. SASAKI, T., "A State-of-the-Art Summary of Techniques for the 

 Prediction of Beach Changes Due to a Breakwater," Report No. 1, 

 Nearshore Environment Research Center, Tokyo, 1976 (in Japanese). 



151. SASAKI, T., and SAKURAMOTO, H., "Field Verification of a Shoreline 

 Simulation Model," Proceedings of the International Conference on 

 Water Resources Engineering, Bangkok, Thailand, 1978. 



Keywords: Detached breakwater. Littoral transport. Numerical model, 

 Tombolo, Wave diffraction 



Several numerical treatments have been presented to predict shore- 

 line changes under natural conditions such as at river deltas and around 

 headlands, as well as the changes brought about by the erection of man- 

 made structures such as groins, jetties, and breakwaters. However, few 

 discussions concerning the validity of these models have been made except 

 those based on laboratory data. This paper presents a verification of 

 the shoreline simulation model of Sasaki (1975) , using very precise field 

 data regarding the shoreline and wave conditions, particularly those on 

 wave direction. Satisfactory agreement is found for engineering purposes 

 in predicting shoreline changes near a breakwater. 



152. SATO, N., and MITSUHASHI , H., "A Means of Preventing Filling of a 

 Harbor Entrance Along a Coast With Alongshore Sand Transport," 

 Proceedings of the 16th Conference on Coastal Engineering in Japan j 

 Japan Society of Civil Engineers, 1969, pp. 125-130 (in Japanese). 



